tev-gamma ray astrophysics with the h.e.s.s. telescopes thomas lohse humboldt university berlin...
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TeV-Gamma Ray Astrophysics
with the H.E.S.S. Telescopes
Thomas LohseHumboldt University Berlin
NordForsk Network Meeting in Astroparticle Physics
Bergen, November 10, 2006
H.E.S.S. CANGAROO III
MAGIC
Veritas
in construction
Cherenkov Telescopes (3rd Generation)
Cosmic ray origin and accelerationSupernova remnantsStarburst galaxiesClusters of galaxiesUnidentified galactic sources/surveys
Astrophysics of compact objectsAGNsMicro-Quasars & Stellar-mass black holesPulsarsGamma ray bursts
CosmologyDiffuse extragalactic radiation fields via cutoff in AGN spectra
Astroparticle physicsNeutralino annihilation in DM halos
TeV -Astronomy: The Physics Shopping List
H.E.S.S.High Energy Stereoscopic System
MPI für Kernphysik, Heidelberg
Humboldt-Universität zu Berlin
Ruhr-Universität Bochum
Universität Erlangen-Nürnberg
Universität Hamburg
Landessternwarte Heidelberg
Universität Tübingen
Ecole Polytechnique, Palaiseau
APC, Paris
Universite Paris VI-VII
CEA Saclay
CESR Toulouse
GAM Montpellier
LAOG Grenoble
Paris Observatory
LAPP Annecy
Durham University
Dublin Inst. for Advanced Studies
NCAC Warsaw
Astronomical Observatory Cracow
Charles University Prag
Yerewan Physics Institute
North-West University, Potchefstroom
University of Namibia, Windhoek
H.E.S.S. Site
Clear sky Galactic centre culminates
in zenith Mild climate Easy access Good local support
(UNAM etc.)
23o16’ S, 16o30’ E, 1800 m asl
Farm Göllschau, Khomas Hochland, 100 km from Windhoek
Farm Göllschau, Khomas Hochland, 100 km from Windhoek
H.E.S.S. Phase I
4 telescopes operational since December 2003Energy threshold (for spectroscopy): 100 GeV
Single shower resolution: 0.1Pointing accuracy: ≲ 20Energy resolution: 20%
June 2002 September 2003 February 2003 December 2003
960 pixel PMT cameraPixel size: 0.16°
On-board electronicsWeight: 900 kg
13m dish, mirror area 107 m2
382 spherical mirrors, f =15mPoint spread 0.03°-0.06°
1. Particle Acceleration in Supernovae
2. The Galactic Centre
3. The Gamma Ray Horizon
4. Gamma Rays from a Super-Massive Black Hole
5. Gamma Rays from a Micro-Quasar
Selected Results from H.E.S.S.
Supernovae
Synchrotron radiation
Pulsar Wind Nebula:Electron wind from central
pulsar heats the cloud
The Standard Candle for TeV -AstronomyCrab Supernova 1054 a.D. d = 2 kpc
optical
1 lig
htye
ar
But what about hadrons (protons and nuclei)?
Cassiopaeia A Supernova 1658 a.D. d = 2,8 kpc
X ray picture
“Shell Type” SNR:
• no electron wind from pulsar
• gamma signal from shell regions not totally drowned in that of electron wind
• good source class to observe hadron acceleration
resolution
H.E.S.S. 2004E 210 GeV
RX J1713.73946
resolution
H.E.S.S. 2004E 210 GeV
RX J1713.73946
First Resolved Supernova Shells in -Rays
H.E.S.S. 2005E 500 GeV
RX J0852.04622
Strong correlation with X-ray intensitiesStrong correlation with X-ray intensities
• SN-Shells are accelerating particles up to at least 200 TeV!• But are these particles protons/nuclei or electrons?
E2 d
N/d
E
log(E)
Stars
radio infrared visible light X-rays VHE -rays
CMB
Dust
CosmicElectron
Accelerators BEe
Electron or Hadron Accelerator?
Synchrotron Radiation Inverse Compton
e
e
EdNd
B, e
e
EdNd BEe
Cosmic Proton
Accelerators
, p
p
Ed
Nd Matter Density
0Synchrotron Radiation of Secondary Electrons
EGRET
2.0 2.0
B 7, 9, 11
GB 7, 9, 11
G
Electron accelerator fits for RX J1713.73946 :• Continuous electron injection over 1000 years• Injection spectrum: power law with cutoff
• IC peak not well described• B-field low for SNR shell
• large & injection rate bremsstrahlung important
• needs tuning at low E
αeE
B 10
G B 10
G
2.0, 2.25, 2.5 2.0, 2.25, 2.5H.E.S.S.H.E.S.S.
Continuous proton injection over 1000 years Injection spectrum: power law, index 2 Different cutoff shapes & diffusion parameters
Proton accelerator fit:
H.E.S.S. RX J1713.73946
Galactic Centre
HESS J1837069
HESS J1834087
HESS J1825137
HESS J1813178
HESS J1804216
G0.90.1HESS J1747281
Galactic CentreHESS J1745290
HESS J1745290
HESS J1713381
RX J1713.73946HESS J1708410
HESS J1702420HESS J1640465
HESS J1634472
HESS J1632478HESS J1616508
HESS J1614518
no visible cut-off rather large mass
measured flux large cross-section and/or DM density
Possible Interpretation: Dark Matter annihilation?
10-13
10-12
10-11
0,1 1 10
E2 F
(E)
[Te
V/c
m2 s]
E [TeV]
20 TeV Neutralino20 TeV Kaluza Klein particle
… unlikely !
H.E.S.S. MAGICGC
Crab
Galactic Centre Neighbourhood
~150 pc
Galactic CentreHESS J1745290
SNR G0.90.1HESS J1747281
EGRET GeV--sources
...point sources subtracted
first resolved detection of diffuse TeV--radiation cosmic rays (hadrons) interacting with molecular clouds
~150 pc
Galactic Centre Neighbourhood
molecular clouds density profiles
HESS J1745290
Cosmic Ray Spectrum at the GC...
diffuse radiation
expected flux for CR spectrum
observed on earth
Cosmic rays are much harder and have 3
larger density around the GC
Cosmic rays are much harder and have 3
larger density around the GC
is very different from the one at earth
Possible reason:
Close-by source population
Possibly single SN-explosion
The Gamma Ray Horizon
General Active Galactic Nuclei (AGN):• Supermassive black holes, M 109 M
• accretion disk and relativistic jets
Blazar-Typ: Jet points towards the earth• Doppler-boost TeV -radiation
Blazars
E
dN/d
E
Measurement of EBL ( Cosmology )
Physics of compact objects,acceleration/absorption in jets,…
EdN
/dE
Absorption in (infrared) extragalactic background light (EBL)
(TeV) + (EBL) e+e-
e+
e-
Cut-off Energy and -Ray Horizon
PG 1553113
H 2356 (x 0.1) = 3.1±0.2 Preliminary
EBL Unfolding of Measured Spectra
1 ES 1101 = 2.9±0.2
EBL
H 2356 (x0.1) = 3.1±0.2
Hardest plausiblesource spectrum = 1.5
Hardest plausiblesource spectrum = 1.5
Too muchEBL
Lower Limits(Galaxy Counts)
New Upper Bound on EBL Density
Direct IRTSMeasurements
Assumed shape for rescaling
H.E.S.S. upper boundfrom spectral shapes of
1ES 1101-232 (z = 0.186) H 2356-309 (z = 0.165)
EBL density seems 2 smaller than expected! Little room for EBL sources other than galaxies (early stars…)
Upper Limits
excluded by H.E.S.S.
M87Gamma Rays from
the Rim of a Super-Massive
Black Hole
M87• Radio Galaxy, Virgo Cluster, d 16 Mpc• Central 3 109 M⊙ Black Hole, RS 1015
cm
• Relativistic Plasma Jet at 30 Blazar
RadioVHE -Rays
host galaxy (optical)
99.9% c.l. extension upper limit
Is there a better way to constrain the source size?
v c
Yes, there sometimes is: Source variability!
source
R
time smearing: R/c
source variability: t* ≳ R/c
shortest observable variability: t ≳ R/c
upper limit on source size: R ≲ c t
θcosβ1Γδ 1
relativistic Doppler factor
reasonable: 1 50
Radio
optical
X-ray
nucleus
knots (jet)
Doubling times of 2 days observed during 2005 high state of M87
cm10R
Rδ5R15
S
S
• Knots in jet are excluded as sources• High energy particles created close to black hole horizon
Gamma Rays from a
Micro-Quasar
LS 5039
Periastron 0
Apastron 0.5
observer
inferior conjunction 0.716
superior conjunction 0.058
Massive star M 20 M⊙
compact object: 1.5-5 M⊙
neutron star or black hole?Orbital Period 3.9 days
Eccentric orbitbinary separation 2-4.5 R
*
LS 5039
Periastron 0
Apastron 0.5
observer
inferior conjunction 0.716
superior conjunction 0.058
Paredes et al. 2000
Faint X-ray emissionslightly variable
Extended pc-scale radio emission possibly from jets (v 0,2 c)
VHE -Ray Lightcurve folded with orbital period 0
0.5
observer
0.716
0.058
Modulation absorption in radiation field central emission ( 1au)
H.E.S.S.H.E.S.S.
VHE Spectral Modulation• modulation strength
strongly energy dependent
• not explainable by pure absorption effects
• complicated interplay between production & absorption mechanisms
The central engine starts to
reveal its physics
The Future: H.E.S.S. Phase II
• Large telescope under construction
• Improve sensitivity: 4 small 1 large better than 8 small
• Reduce threshold to O ( 20 GeV )
Summary• Very successful initial years of H.E.S.S. Phase I
• Many new sources & several fundamental discoveries
• The VHE -ray sky is well populated and complex
• Expect “bright” future